Certain chemicals have been developed for the treatment of turf--to fertilize, to control pests and weeds, to encourage thatch decomposition, to "sweeten" the soil and the like. Many of these chemicals are expensive and must be carefully applied to avoid waste. Others are beneficial for their particular use in the turf but can be damaging if allowed to indiscriminately enter the eco-system by way of evaporation, or migration or run-off during watering.
It is desirable to apply selected chemicals in a judicious, economical manner, minimizing potentially harmful environmental effects. This has nOt been an easy task to accomplish.
It has been found that the most effective manner in which to apply chemicals to turf is to apply the chemical directly to the desired area. This is fairly easy if an above ground, visible leafy growth area is the area to be treated. Standard sprayers or broadcasters are sufficiently effective for such needs. However when roots or thatch areas need treatment, application becomes significantly more problematical. Spray or broadcast chemical spread from above will not easily penetrate through the leafy cover mat to the desired depth. Easy penetration is prohibited because the thatch layer has built up to a substantial thickness and tight consistency. The chemical thus stays on the exposed leafy growth or drops to the top surface area of the thatch where it is easily washed off before proper penetration occurs. Further, some root chemicals are deleterious to the leafy growth by causing "burn" or other unfortunate effects.
Various devices have been developed as attempted solutions to the above problems for penetrating the ground to aid placement of treating materials at selected treatment zones. But most such apparatus are intended for use in agricultural applications where disruption of the ground surface is inconsequential. Such apparatus is not acceptable for use with existing turf.
U.S. Pat. No. 3,602,166 to Peterson, discloses a device for injecting a fluid below the soil surface. The injector includes a number of rotating arms that pierce the ground surface and are intended to be driven to a prescribed depth for injection of a fluid. A similar apparatus is disclosed in U.S. Pat. No. 3,621,799. Steam is introduced into the soil for sterilization purposes. U.S. Pat. No. 4,233,915 to Kordon is of interest to show cultivation of soil by pressurized fluid forced into a subsurface location through use of a number of spaced injector rods.
"Spike" type penetrating applicators as above are difficult to control, to avoid tearing turf as they move along. They also have tendency to provide only "spot" treatment of areas immediately adjacent the area where the spike applicators enter the ground.
Other apparatus have also been utilized to introduce materials into subsurface locations. For example, U.S. Pat. Nos. 4,407,207 and 4,422,392, both disclose seed drills having disk furrow openers for opening a furrow in the ground surface for the purpose of seed planting. The drill is moved along the ground surface and the disk openers are pressed into contact with the ground to produce furrows. Wider openers follow the disks or the disks themselves are angled in order to widen the furrows beyond the thickness dimensions of the disk blades. These patents also disclose use of skids along one side of the furrow opening disk.
The above apparatus may function adequately for seeding in agricultural situations, but they would not function adequately for use in turf since the furrow produced is exaggerated and would produce unacceptable disruption of the existing turf surface. A need therefore has remained for a turf treatment process and apparatus by which chemicals may be placed precisely in the thatch or root zones of the turf without unacceptable disruption of the turf.